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Bolex focus


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#1 Steven Budden

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Posted 11 August 2005 - 12:05 AM

I'm having some irritation with focusing a Bolex SB. When I focus on the ground glass, it appears sharp, but then when I use the lens it won't focus at the shorter focal lengths. Then I can change the diopter to focus on the shorter focal lengths (not the ground glass) and it seems to work fine. And then when I go to look at the ground glass it seems sharp enough. Is this a safe way to set the diopter? Maybe I just can't judge the ground glass focus accurately, because there's nothing to really use as a reference? If it is in focus through the lens does that guarantee it will be in focus on film (if the film plane is positioned correctly)?

Thanks!

Steven
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#2 Sam Wells

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Posted 11 August 2005 - 09:43 AM

I'm confused by what you're saying but...

It's easiest to set the eyepiece diopter with no lens on the camera or the lens thrown way out of focus. Get the grain of the GG as sharp as you can and LOCK it.

This should have no effect on the sharpness of the photographic image.

What lens (es) are you using ? Are you talking about macro ring on the Switar zoom ?
You can't keep focus and zoom if you are in that mode.


-Sam
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#3 Michael Carter

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Posted 11 August 2005 - 09:51 AM

Yep, same deal here.
I thought one should zoom to maximum, set focus to infinity, then set the diopter so the grain is clear and then lock the diopter. One looks at the sky while doing it.
My bolex nonreflex camera has a diopter adjustment on the focus finder which I set that way without any lens on. It has ground glass.
Then, I do the same with the dog leg on a lens but not using the focus finder.
At extreme wide angle settings I can't see if the lens is in focus or not. Perhaps if I were closer to a big object.
Some close up shots of tadpoles were blurry till I set the diopter on my S8 814E properly but raindrops on a window pane were fine?? Got lucky on that shot.
My right eye does need glasses to see properly especially in dim light. However, I set the diopters to maximum and can see clearly in the focus finder and in a dogleg finder or a S8 camera.
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#4 Steven Budden

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Posted 11 August 2005 - 11:50 AM

Alright, maybe I'm just not seeing that it is in focus as wide angles. Yeah, the switar MC zoom. When I set the focus on the ground glass with no lens, all seems fine. But then I can't focus when I put the lens on and zoom out to shorter focal lengths (12.5). At least, it doesn't look clear but I guess it would have to be judging by the distance? I guess I may be having difficulty focusing on the ground glass with no refernce other than specks.

Steven
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#5 Steven Budden

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Posted 11 August 2005 - 11:52 AM

Or maybe the reflex prism is messed up or something? There is a blob of something on the side of it... something black. I don't recall if my other camera had that. Anyway I had no problem with my other bolex but this one is being stubborn.

Steven
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#6 Sam Wells

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Posted 12 August 2005 - 09:11 AM

The lens should hold focus throughout its zoom range.

Eyepiece diopter setting has nothing to do with this.

Bolex vf's aren't the brightest in the world.

There's a mask in the viewfinder, the black blob suggests it is loose.

You need to shoot a test and/or get the camera on a collimator.

-Sam
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#7 Steven Budden

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Posted 12 August 2005 - 02:09 PM

The black blob is a physical blob on the side of the prism which swings out in front of the gate... not in the viewfinder. It seems to be holding the elements together but I can't tell if all have this or only after the prism has been taken apart and put back together?

I understand what you're saying about the diopter. If it is not in focus on the ground glass then the zoom will be out of focus through its whole range... and it if is in focus then the zoom should be in focus in its whole range? I guess it's just difficult to judge focus at the shorter focal lengths.

I'll shoot some tests for sure. No ideas on the footage counter sticking?

Also, side topic: what sort of oil should I use to safely lube this thing and what should I look out for so as not to run into any problems?

Thanks!

Steven
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#8 Sam Wells

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Posted 13 August 2005 - 08:36 AM

I understand what you're saying about the diopter. If it is not in focus on the ground glass then the zoom will be out of focus through its whole range... and it if is in focus then the zoom should be in focus in its whole range? I guess it's just difficult to judge focus at the shorter focal lengths.

<{POST_SNAPBACK}>


By diopter here you mean eyepiece diopter ? It has NO effect on lens focus.

I dunno about this blob, I'm wary of blobs anywhere near a camera gate, unless you're shooting a remake of "The Blob" then you've got a built in holdout matte....

We're going around in circles here, surely there's someone in the Bay area that knows Bolexes and can go over this camera with you ?

-Sam
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#9 Steven Budden

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Posted 14 August 2005 - 10:52 AM

By diopter here you mean eyepiece diopter ? It has NO effect on lens focus.

I dunno about this blob, I'm wary of blobs anywhere near a camera gate, unless you're shooting a remake of "The Blob" then you've got a built in holdout matte....

We're going around in circles here, surely there's someone in the Bay area that knows Bolexes and can go over this camera with you ?

-Sam

<{POST_SNAPBACK}>


Hola Sam,

Thanks for the help. I'll find a bolex tech in the area. I haven't been able to find a good one yet, but there must be one around. It'll work for now.

Thanks!

Steven
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#10 Tim Shim

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Posted 19 August 2005 - 05:44 AM

Hi, I'm having the same problem ... I think.

I just got my Switar 16-100mm POE and tried focusing wide open (16mm) but it won't focus at any focus point. If I zoom in a little, say to 50mm, I can adjust focus and get a clear focused object. But strangely it doesn't focus at all when full wide.

Let me know if you find out the answer, Steven.
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#11 Sam Wells

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Posted 19 August 2005 - 08:41 PM

If I zoom in a little, say to 50mm, I can adjust focus and get a clear focused object. But strangely it doesn't focus at all when full wide.

<{POST_SNAPBACK}>


What happens when you focus @ 50mm and then zoom out, does it hold focus ?

It should or something is wrong.

It can be dificult to gg focus at a wide angel, hence the practice of zooming into focus or using tape measur etc.

Here's a trick, at a wide angle, rock the camera up & down slightly, you can see image on the ground glass "unfreeze"; it will be easier to judge focus.

-Sam
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#12 Steven Budden

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Posted 19 August 2005 - 11:16 PM

Sam,

Thanks for the trick. I'm getting the hang of it. Actually, the aspheron adapter switch was not clicking back into the off position fully so it was still set into "slight" macro. Also, I wasn't used to zooming out and seeing the change in sharpness, which I thought was blurriness, but I've learned it is just the way vision works. This is an awesome lens though. Thanks for the recommendation. Without the auto exposure it is fairly light weight and a little shorter than the old POE I had. It does Macro better than my 25mm macro switar so I sold that and offset the cost a little. I'm loving this film thing.

I'm still curious about your feature. I just watched the Passion of Joan of Arc and that was the most beautiful thing I've ever seen. Well, one of em. Was that one of your influences? Anyway, it inspires me to make silent films. Without having to worry about sound film would be a breeze (relatively), no? Esp black and white, which I'm stuck on anyway.

Steven
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#13 Sam Wells

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Posted 20 August 2005 - 08:44 AM

. Actually, the aspheron adapter switch was not clicking back into the off position fully so it was still set into "slight" macro.

<{POST_SNAPBACK}>


Well that'll sure give you focus issues. If you are in "macro mode" you'll only have proper back focus at one point in the zoom range.

-Sam
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#14 Sam Wells

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Posted 20 August 2005 - 08:49 AM

ost a little. I'm loving this film thing.

I'm still curious about your feature. I just watched the Passion of Joan of Arc and that was the most beautiful thing I've ever seen. Well, one of em. Was that one of your influences? Anyway, it inspires me to make silent films.  Without having to worry about sound film would be a breeze (relatively), no? Esp black and white, which I'm stuck on anyway.

Steven

<{POST_SNAPBACK}>


I'll likely put it out on whatever DVD firmat wins the HD war.

I think my joan of Arc film probably owes much more to Georges Melies' version than Dreyer's !

I finally have a DVD of Bresson's - (that's Robt. Bresson not Luc Besson !!) which I've never seen.

-Sam
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#15 Tim Shim

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Posted 21 August 2005 - 02:37 AM

What happens when you focus @ 50mm and then zoom out, does it hold focus ?

It should or something is wrong.

It can be dificult to gg focus at a wide angel, hence the practice of zooming into focus or using tape measur etc.

Here's a trick, at a wide angle, rock the camera up & down slightly, you can see image on the ground glass "unfreeze"; it will be easier to judge focus.

-Sam

<{POST_SNAPBACK}>


No, Sam, it doesn't. What could be wrong?

The lens is a POE Bolex H16RX. My camera body is a Bolex H16EL. I attached the lens to the Bayonet mount using a C-mount adaptor. Shouldn't this lens be compatible with the EL?

Also, another thing I should note, it seems like when I got the lens, the batteries for the powerzoom isn't working. So I manually turned the zoom, which I guess I shouldn't - it was a bit tight.

Hope someone can help me figure this out.

Cheers,
Tim
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#16 Steven Budden

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Posted 21 August 2005 - 11:28 AM

Do you have the instructions for the POE? You can also use it as a manual lens if you set it. I had one without batteries and I screwed with it a lot without the batteries and it zoomed fine. There are instructions online somewhere.

How much did you pay for the POE? There is a Bayonet mount POE on ebay now for $499, the lowest I've seen it (though it will probably go up a bit).

(Also, if the batteries are dead take them out because those old batteries leak (you probably already have). And is there the close up adapter fitted onto the end?

Steven
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#17 Tim Shim

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Posted 21 August 2005 - 11:39 AM

Hey Steven, thanks for the reply.

Yea, I have the manual for the POE but it nowhere states that you can turn on/off the powerzoom. I tried turning the zoom manually but it seems a little bit tight (like I'm not supposed to), although it works, albeit not smoothly. If you could roughly tell me how to operate this 'on/off' switch, I'm all set - I'd rather work with it manually anyways.

I paid $600 for it. It's a C-mount, but I have the C-mount adaptor to Bayonet for my H16 EL.

I'll try to find some replacement batteries tomorrow to see if it helps any.

What close-up adaptor? I didn't know it came with that. Does it come standard with the lens? It wasn't mentioned in the ebay description nor anywhere else I checked out with regards to this lens.

Tim
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#18 Steven Budden

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Posted 21 August 2005 - 01:56 PM

No, it doesn't come with the close up lens. Just sometimes they come screwed onto the end.

Also, the bayo is a very sturdy mount and the bayo lens is more highly prized (and priced). If the zoom is stiff you may've paid a bit too much for that lens, but it should work fine with the c mount adapter. Many dealers carry those batteries... they're around $30 generally.

Sam, let me know how the new Joan of Arc is... the Bresson.

Steven
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#19 Steven Budden

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Posted 21 August 2005 - 01:59 PM

Close up adapter...

http://cgi.ebay.com/...1QQcmdZViewItem

POE 1

http://cgi.ebay.com/...1QQcmdZViewItem

POE 2

http://cgi.ebay.com/...1QQcmdZViewItem
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#20 Tim Shim

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Posted 22 August 2005 - 01:42 AM

Hah, I think I've found my solution, thought I'd share it with you guys.

For the batteries, I discovered that 2 of the batteries were in fact not dead, but were just a wee bit shorter (by <1mm) and thus were not touching the contact points in the zoom battery compartment cover. My solution was just to fold a small piece of aluminum foil and put it in between the batts and the metal cover. That solved the problem of why the powerzoom wasn't working.

As for the focus problem, I figured that I needed to manually stop down the aperture to f16 to get a somewhat good focus. I found this strange as the previous lens that came with the Bolex (Angenieux 12-120) didn't have this problem even when I opened the aperture all the way up to f2.2. Does anyone know if this is normal or is something really, really wrong with the POE lens?

Sorry if this post isn't really related to the diopter thingy but the problem sounded similar. Thanks for all your help, though, guys.

Tim
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